After trying to resolve my problem with the Nintex support, they suggest to me to create this question on dev talk.
In fact, the problem concern JS on forms so they can't help me.
My problem is the custom validation function in a textarea or other placed in a repeating section.
This custom validation function is only fired for the first line of repeater, after that when to add more lines, custom validation function is never called.
This function is just a call to my method JS included to the form, it permit to replace commas by dots to prevent bad calculation of amount by Nintex (decimal separator VS thousand separator).
Anyone know how can I work around my problem with JS or not... I've already try to use validation rules, regex but it doesn't work when the textarea is define as a double value instead of string by default.
Thank you a lot for your time